Out of curiosity, how does a Marvel/DC crossover come about? Does it have to be the higher ups, senior editors or someone like that, deciding they want to do a crossover, and then assigning a creative team? Or if a writer or two and/or an artist come up with an idea, can they just pitch it to editors the way they would a standard story, and get the ball rolling from there?
To begin with, you’d need a deal between DC and Marvel to do such a thing–and that doesn’t appear to be in the cards on either side at the moment.